A hidden factor in an unhappy relationship, especially ones where partners complain about feeling unappreciated, could be sleep deprivation.

A new study examining how sleep habits can influence expressions of gratitude between romantic partners has been conducted by a group of researchers from the University of California Berkeley. Their findings were presented at the annual meeting of the Society for Personality and Social Psychologists in New Orleans on January 19.

Amie Gordon, a UC Berkeley psychologist and lead investigator of the study said, “Poor sleep may make us more selfish as we prioritize our own needs over our partner’s.”

The study reveals the emotional interdependence that is present between sleep partners. Results show surprisingly compelling evidence that a sleepless night leaves people less accustomed to the feelings and needs of their partner.

Bedtime can often turn into a battleground, because of sheet-pulling, loud snoring, or one person typing on a laptop while the other tosses and turns.

Gordon said, “You may have slept like a baby, but if your partner didn’t, you’ll probably both end up grouchy.”

The authors point out that many people claim they are just too busy to sleep, even announcing how well they are able to function on minimum sleep. This particular observation made Amie Gordon particularly interested in how lack of sleep might affect relationships.

Over 60 couples ranging in age from 18 to 56 took part in the study. In the first part of the experiment, the volunteers wrote down their sleep patterns and how a poor or good night’s rest affected their gratitude towards their partner.

In the second part, the participants were observed by videotape while completing problem-solving tasks. Results showed that partners who slept poorly exhibited less appreciation for their significant other.

In an additional part of the study, participants were asked to record five things they were grateful for as their last night’s sleep was examined for quality by the researchers. Those people who had a poor night’s sleep felt less appreciative after listing the five things, in comparison to those who had slept well.

In conclusion, the results showed that poor sleepers have a tougher time feeling appreciative of their partners, and really knowing their true value.

Written by Kelly Fitzgerald